Understanding the emplacement and evolution of large, long-lived plutons in the middle crust is essential in comprehending igneous crustal growth and how arcs operate. One challenge is that the plutonic rock record seldom preserves the initial stages of pluton growth. The initial stages of growth, however, may give us clues on the size and compositions of the first intruding magma batches and if and how they coalesce to form interconnected magma mush bodies. Early stages of pluton growth are preserved in the 95--93 Kuna Crest lobe of the 95--85 Ma, 1,100 km2, normally zoned Tuolumne Intrusive Complex (TIC) in the central Sierra Nevada batholith, CA. The Kuna Crest is composed of cm- to m-scale sheets at the margins to km-scale, irregular bodies in the interior of the lobe. Compositions range from granodiorite to gabbroic diorite with knife sharp to gradational contacts. Petrographic analysis reveals varying mineral abundances and textures across subunits, indicating different petrogenic histories. Magnesiohornblende signatures identify the sheeted sub-units as individual batches of magma that underwent complete in-situ fractional crystallization at intermediate to low magmatic temperatures and record the pre- and co-precipitation of other minerals in the assemblage. At the initiation of the Kuna Crest lobe of the TIC, magma increments intruded into the emplacement level as sheet-like bodies without coalescing to form larger magma mush bodies. In contrast, in the interior of the lobe, individual increments grew to larger interconnected magma mush regions represented by the lobe units.